This invention relates to envelope constructions and, particularly, to envelope constructions for use with conventional table or desk top laser printers.
Presently, it is difficult for standard business envelopes to be fed into a table or desk top laser printer without the addition of a specially constructed envelope feed device. In addition, and even with this feed device, standard solid-pasted envelopes will pucker and/or wrinkle when processed through a laser printer as a result of the heat and pressure applied during the printing process.
The present invention solves these problems in a unique way by utilizing the heat fusing rolls of the laser printer, which are employed to fix the toner on the printed substrate, to activate a heat sealable or heat activatable adhesive provided about three peripheral borders of at least one of the envelope forming panels to seal the front and rear panels of the envelope along the borders to thereby form a conventional envelope pocket.
More specifically, in the present invention, a pair of sheets or webs (in discrete or continuous form) are superimposed and adhesively secured along a single leading edge thereof. The leading edge in this context refers to a forward edge relative to the direction of feeding. The upper and lower sheets or webs incorporate front and rear envelope panels with the front panel in direct overlying and vertically aligned relationship with the rear panel. It is also a feature of the invention that the envelope panels have at least two edges which coincide with corresponding edges of the web or sheet to minimize subsequent trimming to finished form.
The front panel of the envelope includes a foldable sealing panel portion which is provided on its rearward face with an adhesive, and preferably with a rewettable adhesive. Thus, in use, the sealing panel may be folded over the rear envelope panel and sealed in a conventional manner via application of moisture to the rewettable adhesive.
The rear sheet or web is provided on its front face with an antistick composition, and preferably a moisture barrier composition, directly underlying the rewettable adhesive on the superimposed foldable sealing panel to prevent accidental and unintended sticking of the sealing panel portion to the underlying sheet or web during production of the envelope.
At the same time, the envelope border portions, with the exception of the border defined by the foldable sealing flap portion, are provided with a heat activatable adhesive, applied in any conventional manner. The adhesive is preferably applied only to the front face of the rear panel, but may be applied additionally or alternatively to the rear face of the front panel.
To print and finalize the formation of the envelope construction, the superimposed webs or sheets are fed into a printing machine, such as a toner based table or desk top laser printer, with the sheets or webs adhered only along the forward leading edge extending across the sheets or webs, i.e., transverse to the direction of feeding.
After the envelope (typically only the front panel) has been printed with return address information and the like, the webs or sheets are passed between a pair of heat fusing rollers which not only fix the toner, but also activate the adhesive about the three peripheral borders of one of the envelope panels, so as to securely fasten one panel to the other and thereby form the envelope, including a pocket portion sealed on three sides and open on one side.
Subsequently, the individual envelopes are separated from the webs manually, or alternatively, webs or sheets may be fed into a trimming machine for removal of all or part of the web or sheet material lying outside the bounds of the envelope panels. The web portions which do not form part of the envelope per se, many also be printed and used as a voucher, invoice, or the like to be inserted in the envelope and mailed to a customer, client, etc.
In one exemplary embodiment, a standard size 10 business envelope may be oriented lengthwise of standard 81/2" wide webs or sheets in such a way as to minimize the amount of paper required to be trimmed. In another exemplary embodiment, the envelope is oriented cross-wise to the longitudinally extending webs or sheets to form a smaller envelope in a manner that also minimizes trimming.
In either case, the webs or sheets may be in continuous or discrete form. If continuous, transverse lines of perforations extending across the webs or sheets may be employed to facilitate separation of the individual envelopes and, if appropriate, associated voucher, invoice, or the like. The separation may occur before or after, but preferably after the printing operation.
Accordingly, in its broader aspects, the invention relates to an envelope blank assembly which, in one exemplary embodiment, comprises a first sheet incorporating a front panel portion and foldable sealing flap portion of an envelope, superimposed and fixed to a second sheet incorporating a rear panel portion, wherein at least one of the first and second sheets has a heat activatable adhesive extending along three peripheral edges of one of the envelope panels, and engaging the other of the envelope panels. The foldable sealing flap portion of the envelope has a rewettable adhesive applied to its rearward face, while a corresponding portion of the second sheet lying directly beneath the foldable sealing flap portion has an antistick composition applied thereto.
The present invention also relates to a process of forming and printing an envelope comprising, broadly, the steps of (1) superimposing a pair of paper sheets, each of which incorporates an envelope panel portion, wherein one or more of the panel portions are provided with a heat activatable adhesive in predetermined border areas; and (2) passing the sheets through a printing device including heating means such that the heat activatable adhesive on the one or more panel portions is activated by the heating means during printing to secure the envelope panel portions together.
From the above, it will be appreciated that the present invention solves particular problems with respect to the ability and/or ease with which standard business envelope constructions can be printed by conventional toner-based table or desk top laser printers. The invention is particularly advantageous in that it reduces the number of steps required to form and print the envelope, and in that it enables envelopes to be printed in standard table or desk top laser printers without requiring specially designed feed devices heretofore required in the prior art to align and properly feed conventional envelopes.
Further objects and advantages of the invention will become apparent from the detailed description which follows.